四氢叶酸辅酶模型1,2,3-三取代咪唑啉盐的质谱裂解行为

Tetrahydrofolate Coenzyme Models. The Mass Spectrometric Analysis of 1,2,3 Trisubstituted Imidazolinium Salts

讨论了１ ，２ ，３不对称取代咪唑啉盐各种离子的生成途径以及取代基对裂解方式的影响并分析了该类化合物的主要裂解方式。在所有实验中均有 ｍ／ｚ ＝ １２７（ Ｉ＋ ） 的离子峰和有机正离子 Ａ 峰存在，表明化合物１ 和２ 均为有机正离子和碘离子形成的盐。化合物１ 和２ 的质谱有相似的裂解方式：有机正离子发生失掉氮原子上的一个取代基而保留咪唑啉环产生 Ｄ， Ｅ， Ｆ 离子的裂解方式。更重要的是咪唑啉环有相同的裂解方式： Ｃ２ Ｎ３ 键和 Ｃ５ Ｎ１ 键同时断裂产生 Ｇ 离子碎片，以及 Ｃ２ Ｎ３ 键和 Ｃ４ Ｃ５ 键同时断裂产生 Ｈ 离子碎片。由于化合物１ 和２ 环上所连接的取代基不同而导致了其质谱裂解方式和程度的差异。化合物２ 的有机正离子 Ａ部分较稳定，质谱中表现为基峰，其 Ｅ， Ｆ 离子峰很弱；化合物１ 的有机正离子 Ａ 稳定性差，其相对丰度很小，其 Ｅ， Ｆ 离子峰较强。化合物１ｃ ，１ｄ ，１ｅ 的质谱中出现了比 Ａ 离子少三个单位的 Ｃ 离子峰，这是一种较特殊的裂解方式。

In the chemical imitation study of the one carbon unit transfer manner of tetrahydrofolate coenzyme, we designed and synthesized a series of 1,2,3 trisubstituted imidazolinium salts (1 and 2) serving as tetrahydrofolate coenzyme models. Their properties and the abilities of transferring one carbon unit were studied. Their structures were proved by \+1 HNMR,\+ 13 CNMR,IR,elementary analysis etc. Here the mass spectral behavior were reported. In the mass spectra, we found that the peak m/z=137(I+) and the organic cation(A)peak present in all experiments in stead of the molecular ion peak. Compounds 1 and 2 have similar fragmentation pattern. The organic cations could lose one of the substituents linked to nitrogen atoms and reserve the ring to give out D, E, F fragment ions. More important is their imidazolinium rings splitted in the similar manner: the bonds C\+2-N\+3 and C\+5-N\+1 or C\+2-N\+3 and C\+4-C\+5 brokedown and produced G and H fragments. The relative abundances were high, some were the base peak and others were the second main peaks. Because of the different substituents, the imidazolinium rings have different stability. A peaks of compound 2 were high and were the base peaks (expect 2d), the E,F peaks were low or none. But for compound 1,the A peaks were low and E,F peaks were high. In the mass spectra of 1c,1d,1e appeared C peaks (3 units less than A). This was a special rupture manner.